The actual useable data transfer rate may vary.
Generally - depending on the server tariff - 10MBit, 100MBit or 1GigaBit ports are available for the server. With this port speed the server is connected to a switch in the network segment.
Within the network segment several servers and switches are sharing the backbone channels. So the capacities can be used optimally.
Depending on the utilization of the capacities and used port speed (10, 100, 1000MBit) a speed between 40 and 80% of the theoretically possible speed is available.
This approach of "shared traffic" is usual with all big server providers and enables the affordable offer of dedicated servers.
Alternatively there is "dedicated traffic" ("unshared/reserved bandwidth") available, which costs in turn ten to twenty times more than the average.